# 录像实现方案

## 开发流程

在获取到相机支持的输出流能力后，开始创建录像流，开发流程如下。

![Recording Development Process](figures/recording-development-process.png)


## 完整示例
[各类Context的获取方式](../application-models/application-context-stage.md)
```ts
import camera from '@ohos.multimedia.camera';
import type { BusinessError } from '@ohos.base';
import media from '@ohos.multimedia.media';
import type featureAbility from '@ohos.ability.featureAbility';

async function videoRecording(context: featureAbility.Context, surfaceId: string): Promise<void> {
  // 创建CameraManager对象
  let cameraManager: camera.CameraManager = camera.getCameraManager(context);
  if (!cameraManager) {
    console.error("camera.getCameraManager error");
    return;
  }

  // 监听相机状态变化
  cameraManager.on('cameraStatus', (err: BusinessError, cameraStatusInfo: camera.CameraStatusInfo) => {
    console.log(`camera : ${cameraStatusInfo.camera.cameraId}`);
    console.log(`status: ${cameraStatusInfo.status}`);
  });

  // 获取相机列表
  let cameraArray: Array<camera.CameraDevice> = cameraManager.getSupportedCameras();
  if (cameraArray.length <= 0) {
    console.error("cameraManager.getSupportedCameras error")
    return;
  }
  // 获取相机设备支持的输出流能力
  let cameraOutputCap: camera.CameraOutputCapability = cameraManager.getSupportedOutputCapability(cameraArray[0]);
  if (!cameraOutputCap) {
    console.error("cameraManager.getSupportedOutputCapability error")
    return;
  }
  console.log("outputCapability: " + JSON.stringify(cameraOutputCap));

  let previewProfilesArray: Array<camera.Profile> = cameraOutputCap.previewProfiles;
  if (!previewProfilesArray) {
    console.error("createOutput previewProfilesArray == null || undefined");
  }

  let photoProfilesArray: Array<camera.Profile> = cameraOutputCap.photoProfiles;
  if (!photoProfilesArray) {
    console.error("createOutput photoProfilesArray == null || undefined");
  }

  let videoProfilesArray: Array<camera.VideoProfile> = cameraOutputCap.videoProfiles;
  if (!videoProfilesArray) {
    console.error("createOutput videoProfilesArray == null || undefined");
  }

  let metadataObjectTypesArray: Array<camera.MetadataObjectType> = cameraOutputCap.supportedMetadataObjectTypes;
  if (!metadataObjectTypesArray) {
    console.error("createOutput metadataObjectTypesArray == null || undefined");
  }

  // 配置参数以实际硬件设备支持的范围为准
  let aVRecorderProfile: media.AVRecorderProfile = {
    audioBitrate: 48000,
    audioChannels: 2,
    audioCodec: media.CodecMimeType.AUDIO_AAC,
    audioSampleRate: 48000,
    fileFormat: media.ContainerFormatType.CFT_MPEG_4,
    videoBitrate: 2000000,
    videoCodec: media.CodecMimeType.VIDEO_MPEG4,
    videoFrameWidth: 640,
    videoFrameHeight: 480,
    videoFrameRate: 30
  };
  let aVRecorderConfig: media.AVRecorderConfig = {
    audioSourceType: media.AudioSourceType.AUDIO_SOURCE_TYPE_MIC,
    videoSourceType: media.VideoSourceType.VIDEO_SOURCE_TYPE_SURFACE_YUV,
    profile: aVRecorderProfile,
    url: 'fd://', // 文件需先由调用者创建，赋予读写权限，将文件fd传给此参数，eg.fd://45--file:///data/media/01.mp4
    rotation: 0, // 合理值0、90、180、270，非合理值prepare接口将报错
    location: { latitude: 30, longitude: 130 }
  };

  let avRecorder: media.AVRecorder;
  media.createAVRecorder((error: BusinessError, recorder: media.AVRecorder) => {
    if (recorder != null) {
      avRecorder = recorder;
      console.log('createAVRecorder success');
    } else {
      console.log(`createAVRecorder fail, error:${error}`);
    }
  });

  avRecorder.prepare(aVRecorderConfig, (err: BusinessError) => {
    if (err == null) {
      console.log('prepare success');
    } else {
      console.log(`prepare failed. error: ${JSON.stringify(err)}`);
    }
  })

  let videoSurfaceId: string = null; // 该surfaceID用于传递给相机接口创造videoOutput
  avRecorder.getInputSurface((err: BusinessError, surfaceId: string) => {
    if (err == null) {
      console.log('getInputSurface success');
      videoSurfaceId = surfaceId;
    } else {
      console.log(`getInputSurface failed. error: ${JSON.stringify(err)}`);
    }
  });

  // 创建VideoOutput对象
  let videoOutput: camera.VideoOutput;
  try {
    videoOutput = cameraManager.createVideoOutput(videoProfilesArray[0], videoSurfaceId);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to create the videoOutput instance. error: ${JSON.stringify(err)}`);
  }

  // 监听视频输出错误信息
  videoOutput.on('error', (error: BusinessError) => {
    console.log(`Preview output error code: ${error.code}`);
  });

  //创建会话
  let captureSession: camera.CaptureSession;
  try {
    captureSession = cameraManager.createCaptureSession();
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to create the CaptureSession instance. error: ${JSON.stringify(err)}`);
  }

  // 监听session错误信息
  captureSession.on('error', (error: BusinessError) => {
    console.log(`Capture session error code: ${error.code}`);
  });

  // 开始配置会话
  try {
    captureSession.beginConfig();
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to beginConfig. error: ${JSON.stringify(err)}`);
  }

  // 创建相机输入流
  let cameraInput: camera.CameraInput;
  try {
    cameraInput = cameraManager.createCameraInput(cameraArray[0]);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to createCameraInput. error: ${JSON.stringify(err)}`);
  }

  // 监听cameraInput错误信息
  let cameraDevice: camera.CameraDevice = cameraArray[0];
  cameraInput.on('error', cameraDevice, (error: BusinessError) => {
    console.log(`Camera input error code: ${error.code}`);
  });

  // 打开相机
  try {
    await cameraInput.open();
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to open cameraInput. error: ${JSON.stringify(err)}`);
  }

  // 向会话中添加相机输入流
  try {
    captureSession.addInput(cameraInput);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to add cameraInput. error: ${JSON.stringify(err)}`);
  }

  // 创建预览输出流,其中参数 surfaceId 参考下面 XComponent 组件，预览流为XComponent组件提供的surface
  let previewOutput: camera.PreviewOutput;
  try {
    previewOutput = cameraManager.createPreviewOutput(previewProfilesArray[0], surfaceId);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to create the PreviewOutput instance. error: ${JSON.stringify(err)}`);
  }

  // 向会话中添加预览输入流
  try {
    captureSession.addOutput(previewOutput);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to add previewOutput. error: ${JSON.stringify(err)}`);
  }

  // 向会话中添加录像输出流
  try {
    captureSession.addOutput(videoOutput);
  } catch (error) {
    let err = error as BusinessError;
    console.error(`Failed to add videoOutput. error: ${JSON.stringify(err)}`);
  }

  // 提交会话配置
  try {
    await captureSession.commitConfig();
  } catch (error) {
    let err = error as BusinessError;
    console.error(`captureSession commitConfig error: ${JSON.stringify(err)}`);
  }

  // 启动会话
  try {
    await captureSession.start();
  } catch (error) {
    let err = error as BusinessError;
    console.error(`captureSession start error: ${JSON.stringify(err)}`);
  }

  // 启动录像输出流
  videoOutput.start((err: BusinessError) => {
    if (err) {
      console.error(`Failed to start the video output. error: ${JSON.stringify(err)}`);
      return;
    }
    console.log('Callback invoked to indicate the video output start success.');
  });

  // 开始录像
  try {
    await avRecorder.start();
  } catch (error) {
    let err = error as BusinessError;
    console.error(`avRecorder start error: ${JSON.stringify(err)}`);
  }

  // 停止录像输出流
  videoOutput.stop((err: BusinessError) => {
    if (err) {
      console.error(`Failed to stop the video output. error: ${JSON.stringify(err)}`);
      return;
    }
    console.log('Callback invoked to indicate the video output stop success.');
  });

  // 停止录像
  try {
    await avRecorder.stop();
  } catch (error) {
    let err = error as BusinessError;
    console.error(`avRecorder stop error: ${JSON.stringify(err)}`);
  }

  // 停止当前会话
  captureSession.stop();

  // 释放相机输入流
  cameraInput.close();

  // 释放预览输出流
  previewOutput.release();

  // 释放录像输出流
  videoOutput.release();

  // 释放会话
  captureSession.release();

  // 会话置空
  captureSession = null;
}
```